The present invention relates to a novel isolated structural gene of urease, to a recombinant DNA capable of replicating in Escherichia coli carrying a vector into which said structural gene has been introduced, and to a process for producing urease, which comprises cultivating Escherichia coli carrying said recombinant DNA and recovering urease from the culture mixture.
Urease (EC 3.5.1.5) is an enzyme which catalyzes decomposition of urea to form ammonia and carbon dioxide, and is widely found in plants, animals and microorganisms.
Those derived from jack beans (Canavalia ensiformic) and from microorganisms have already been produced industrially (Japanese Patent Kokai No.86081/1983 and No.17987/1984) and are used as a drug for clinical diagnosis.
In addition, structural genes have been reported with the urease derived from Proteus mirabilis, [Bradley D. Jones & Harry L. T. Mobley; J. Bacteriol., 171, 6414-6422 (1989)], Staphylococcus saprophyticus [Soren Garermann & Reihard Marre; Infect. Immun., 57, 2998-3002 (1989)], Klebsiella pneumoniae [Gerald F. Gerlach, et al.; FEMS Microbiol. Lett., 50, 131-135 (1983)], Providencia stuartii [Harry L. T. Mobley, et al.; Infect. Immun., 54, 161-169 (1986)], Escherichia coli [Carleen M. Collins & Stanley Falkow; J. Bacteriol., 170, 1041-1045 (1988)], and Bacillus pasteurii [Kor. J. Appl. Microbiol. Bioeng., 13, 297-302 (1985)]. Expression of urease gene in Escherichia coli is reported with Staphylococcus saprophyticus, Klebsiella pneumoniae, Providencia stuartii and Bacillus pasteurii among the literatures shown above.
The present inventors formerly reported a novel urease more stable than known enzymes [Japanese Patent Kokai No.175174/1987].
However, production of said highly stable urease utilizing the techniques of genetic engineering has not been reported yet.